1. Field of the Invention
This invention pertains generally to the field of aircraft displays that depict taxiway clearance information.
2. Description of the Related Art
A great deal of attention in the aviation industry has been paid to the avoidance of runway incursions. A runway incursion is an incident at an airport which adversely affects runway safety. Runway incursions are the most noticeable form of taxi navigation errors. Increased scrutiny by regulatory authorities has only heightened the awareness of the safety issues related to runway incursions. Taxi navigation errors cause many runway incursions and present potential collision hazards.
Inventors have addressed the issue of runway incursion. For example, Carrico et al addresses the issue of runway incursion in U.S. patent application Ser. No. 13/236,676 entitled “System, Apparatus, and Method for Generating Airport Surface Incursion Alert.” In another example, Corcoran III addresses the issue of runway incursion in U.S. Pat. No. 6,606,563 entitled “Incursion Alerting System.” In Corcoran III, a system is presented for alerting the occupant of a vehicle that the vehicle is approaching a zone of awareness, where the zone of awareness surrounds a runway and is based upon a reference such as a line or line segment that defines a runway centerline. When the vehicle is within a predetermined value of the zone of awareness, an alert is provided to the occupant. That is, a processor calculates the difference between the zone of awareness and the aircraft and initiates the alerting device if the distance is within predetermined parameters. The processor may also take into account the direction of travel and/or velocity when initiating the alert to adjust predetermined parameters by, for instance, increasing a fixed distance at which the alert is initiated if the vehicle is approaching the zone of awareness. Alternatively, the processor may adjust values corresponding to the location of the vehicle, location of the reference upon which the zone of awareness is based, or the distance between the vehicle location and reference location, according to the velocity, direction of travel, or both.
In another example, Roe et al discusses an on-ground Runway Awareness and Advisory System (“RAAS”) in U.S. Pat. No. 7,587,278 entitled “Ground Operations and Advanced Runway Awareness and Advisory System.” In Roe, the RAAS enhances situational awareness during taxiing by providing advisories to the pilot. The RAAS algorithm determines whether the aircraft will cross a runway or whether the aircraft is on the runway and provides applicable advisories. For landing and on-ground aircraft, the RAAS constructs an advisory annunciation envelope or bounding box from which situational awareness annunciations are announced. An Aural/Visual Advisory Processing function generates an advisory when a runway encounter is triggered when an aircraft enters the envelope surrounding the runway that could be augmented as a function of ground speed.
In another example, Krenz et al discusses a system for providing taxi navigation information to a pilot of an aircraft in U.S. Pat. No. 7,974,773 entitled “Methods and Devices of an Aircraft Taxi Navigation System.” In Krenz, taxi navigation symbology representative of airport signs comprised of graphical objects are presented to the pilot in an egocentric manner or a “pilot's eye” view and not a “bird's eye” view such as reading a roadmap. There were several novel aspects therein including the use of ICAO taxiway and runway signage symbols depicted in an egocentric format on the primary cockpit indicator, the placement of symbologies of runway signage to indicate upcoming left and right turns and current airport surface, the use of distance indications adjacent to the symbologies, and display of a plurality of turns to the left and to the right.
Despite many improvements, situational awareness of the runway environment still remains a significant safety issue.